William's syndrome (WMS) is a genetically based syndrome that results in a cognitive profile of peaks and valleys of cognitive abilities in the mature state. We investigate the development of this unusual profile in WMS Children in order to provide clues to alternative theories of language, cognition, and brain organization. Contrasting Development of Language and General Cognition in WMS. Importantly, in the development of first words, WMS and Down syndrome (DNS) children are equally delayed, and it is only as grammar emerges that WMS appear to show an increasing advantage over DNS. We will examine both on- line and off-line measures focusing and dissociations between language and other domains, as well as the development of discourse functions. a) The Intersection of Language and Affect in Discourse. We investigate hyperaffectivity and language in developing WMS children, which may set them apart from other Center populations. b) The Dissociation between Language and Spatial Representation in WMS. Because of their severe spatial cognitive deficit, WMS children provide a special opportunity to probe potential between language and spatial representations. Contrasting Development: The Dissociation between Space and Face Processing in WMS. WMS results in a highly specific impairment in spatial construction. In contrast, face processing shows strength across paradigms. Thus, WMS children provide a powerful vehicle for investigating the developmental separability of functions within the visual domain. Brain Organization in the Developing Child with WMS. We will examine the hypothesis that developmental aspects of language and spatial functions in WMS may be mediated by neural systems that differ in major ways from those in normal populations. We also hypothesize that there may be differential dysfunction in the dorsal as opposed to the ventral stream of visual processing in WMS, addressed vial electrophysiological and functional MRI studies. Comparison of the profiles of developing WMS Children and other Center populations can provide insights into issues of the genetic bases of higher cortical functions.